One of the methods to recover oil from medium and low viscosity in complex reservoirs uses air injection leading to oil combustion. In this case the oxygen in the air burns the heavier components of the oil, generating a heat wave leading to vaporization of lighter components. In this work, we consider a simple model for air injection in light oil reservoir containing only one component in dry porous rock as our goal is to improve understanding of the basics of the oxidation/evaporation/ condensation mechanism. The model equations are solved both numerically and analytically. A comparison shows the effect of diffusion/ conduction on the result. Both the analytical and numerical models show that vaporization occurs upstream of the combustion zone.